Year	Percent
1998-01-01	51.925
1999-01-01	51.400
2000-01-01	50.600
2001-01-01	51.300
2002-01-01	51.900
2003-01-01	51.425
2004-01-01	51.175
2005-01-01	51.850
2006-01-01	52.450
2007-01-01	53.250
2008-01-01	53.550
2009-01-01	52.650
2010-01-01	51.750
2011-01-01	51.825
2012-01-01	52.050
2013-01-01	51.350
2014-01-01	51.075
2015-01-01	50.700
2016-01-01	50.275
2017-01-01	50.550